/*******************************************************************************
 * Copyright (c) 2000, 2003 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package net.sourceforge.phpdt.core;

import org.eclipse.core.runtime.IPath;

/**
 * An entry on a Java project classpath identifying one or more package fragment
 * roots. A classpath entry has a content kind (either source,
 * <code>K_SOURCE</code>, or binary, <code>K_BINARY</code>), which is
 * inherited by each package fragment root and package fragment associated with
 * the entry.
 * <p>
 * A classpath entry can refer to any of the following:
 * <ul>
 * 
 * <li>Source code in the current project. In this case, the entry identifies a
 * root folder in the current project containing package fragments and
 * <code>.java</code> source files. The root folder itself represents a
 * default package, subfolders represent package fragments, and
 * <code>.java</code> files represent compilation units. All compilation units
 * will be compiled when the project is built. The classpath entry must specify
 * the absolute path to the root folder. Entries of this kind are associated
 * with the <code>CPE_SOURCE</code> constant. Source classpath entries can
 * carry patterns to exclude selected files. Excluded <code>.java</code>
 * source files do not appear as compilation units and are not compiled when the
 * project is built. </li>
 * 
 * <li>A binary library in the current project, in another project, or in the
 * external file system. In this case the entry identifies a JAR (or root
 * folder) containing package fragments and <code>.class</code> files. The
 * classpath entry must specify the absolute path to the JAR (or root folder),
 * and in case it refers to an external JAR, then there is no associated
 * resource in the workbench. Entries of this kind are associated with the
 * <code>CPE_LIBRARY</code> constant.</li>
 * 
 * <li>A required project. In this case the entry identifies another project in
 * the workspace. The required project is used as a binary library when
 * compiling (that is, the builder looks in the output location of the required
 * project for required <code>.class</code> files when building). When
 * performing other "development" operations - such as code assist, code
 * resolve, type hierarchy creation, etc. - the source code of the project is
 * referred to. Thus, development is performed against a required project's
 * source code, and compilation is performed against a required project's last
 * built state. The classpath entry must specify the absolute path to the
 * project. Entries of this kind are associated with the
 * <code>CPE_PROJECT</code> constant. Note: referencing a required project
 * with a classpath entry refers to the source code or associated
 * <code>.class</code> files located in its output location. It will also
 * automatically include any other libraries or projects that the required
 * project's classpath refers to, iff the corresponding classpath entries are
 * tagged as being exported (<code>IClasspathEntry#isExported</code>).
 * Unless exporting some classpath entries, classpaths are not chained by
 * default - each project must specify its own classpath in its entirety.</li>
 * 
 * <li> A path beginning in a classpath variable defined globally to the
 * workspace. Entries of this kind are associated with the
 * <code>CPE_VARIABLE</code> constant. Classpath variables are created using
 * <code>JavaCore#setClasspathVariable</code>, and gets resolved, to either a
 * project or library entry, using
 * <code>JavaCore#getResolvedClasspathVariable</code>. It is also possible to
 * register an automatic initializer (<code>ClasspathVariableInitializer</code>),
 * which will be invoked through the extension point
 * "net.sourceforge.phpdt.core.classpathVariableInitializer". After resolution,
 * a classpath variable entry may either correspond to a project or a library
 * entry. </li>
 * 
 * <li> A named classpath container identified by its container path. A
 * classpath container provides a way to indirectly reference a set of classpath
 * entries through a classpath entry of kind <code>CPE_CONTAINER</code>.
 * Typically, a classpath container can be used to describe a complex library
 * composed of multiple JARs, projects or classpath variables, considering also
 * that containers can be mapped differently on each project. Several projects
 * can reference the same generic container path, but have each of them actually
 * bound to a different container object. The container path is a formed by a
 * first ID segment followed with extra segments, which can be used as
 * additional hints for resolving this container reference. If no container was
 * ever recorded for this container path onto this project (using
 * <code>setClasspathContainer</code>, then a
 * <code>ClasspathContainerInitializer</code> will be activated if any was
 * registered for this container ID onto the extension point
 * "net.sourceforge.phpdt.core.classpathContainerInitializer". A classpath
 * container entry can be resolved explicitly using
 * <code>JavaCore#getClasspathContainer</code> and the resulting container
 * entries can contain any non-container entry. In particular, it may contain
 * variable entries, which in turn needs to be resolved before being directly
 * used. <br>
 * Also note that the container resolution APIs include an IJavaProject
 * argument, so as to allow the same container path to be interpreted in
 * different ways for different projects. </li>
 * </ul>
 * </p>
 * The result of <code>IJavaProject#getResolvedClasspath</code> will have all
 * entries of type <code>CPE_VARIABLE</code> and <code>CPE_CONTAINER</code>
 * resolved to a set of <code>CPE_SOURCE</code>, <code>CPE_LIBRARY</code>
 * or <code>CPE_PROJECT</code> classpath entries.
 * <p>
 * Any classpath entry other than a source folder (kind <code>CPE_SOURCE</code>)
 * can be marked as being exported. Exported entries are automatically
 * contributed to dependent projects, along with the project's default output
 * folder, which is implicitly exported, and any auxiliary output folders
 * specified on source classpath entries. The project's output folder(s) are
 * always listed first, followed by the any exported entries.
 * <p>
 * This interface is not intended to be implemented by clients. Classpath
 * entries can be created via methods on <code>JavaCore</code>.
 * </p>
 * 
 * @see JavaCore#newLibraryEntry
 * @see JavaCore#newProjectEntry
 * @see JavaCore#newSourceEntry
 * @see JavaCore#newVariableEntry
 * @see JavaCore#newContainerEntry
 * @see ClasspathVariableInitializer
 * @see ClasspathContainerInitializer
 */
public interface IClasspathEntry {

	/**
	 * Entry kind constant describing a classpath entry identifying a library. A
	 * library is a folder or JAR containing package fragments consisting of
	 * pre-compiled binaries.
	 */
	int CPE_LIBRARY = 1;

	/**
	 * Entry kind constant describing a classpath entry identifying a required
	 * project.
	 */
	int CPE_PROJECT = 2;

	/**
	 * Entry kind constant describing a classpath entry identifying a folder
	 * containing package fragments with source code to be compiled.
	 */
	int CPE_SOURCE = 3;

	/**
	 * Entry kind constant describing a classpath entry defined using a path
	 * that begins with a classpath variable reference.
	 */
	int CPE_VARIABLE = 4;

	/**
	 * Entry kind constant describing a classpath entry representing a name
	 * classpath container.
	 * 
	 * @since 2.0
	 */
	int CPE_CONTAINER = 5;

	/**
	 * Returns the kind of files found in the package fragments identified by
	 * this classpath entry.
	 * 
	 * @return <code>IPackageFragmentRoot.K_SOURCE</code> for files containing
	 *         source code, and <code>IPackageFragmentRoot.K_BINARY</code> for
	 *         binary class files. There is no specified value for an entry
	 *         denoting a variable (<code>CPE_VARIABLE</code>) or a
	 *         classpath container (<code>CPE_CONTAINER</code>).
	 */
	int getContentKind();

	/**
	 * Returns the kind of this classpath entry.
	 * 
	 * @return one of:
	 *         <ul>
	 *         <li><code>CPE_SOURCE</code> - this entry describes a source
	 *         root in its project
	 *         <li><code>CPE_LIBRARY</code> - this entry describes a folder
	 *         or JAR containing binaries
	 *         <li><code>CPE_PROJECT</code> - this entry describes another
	 *         project
	 * 
	 * <li><code>CPE_VARIABLE</code> - this entry describes a project or
	 * library indirectly via a classpath variable in the first segment of the
	 * path *
	 * <li><code>CPE_CONTAINER</code> - this entry describes set of entries
	 * referenced indirectly via a classpath container
	 * </ul>
	 */
	int getEntryKind();

	/**
	 * Returns the set of patterns used to exclude resources associated with
	 * this source entry.
	 * <p>
	 * Exclusion patterns allow specified portions of the resource tree rooted
	 * at this source entry's path to be filtered out. If no exclusion patterns
	 * are specified, this source entry includes all relevent files. Each path
	 * specified must be a relative path, and will be interpreted relative to
	 * this source entry's path. File patterns are case-sensitive. A file
	 * matched by one or more of these patterns is excluded from the
	 * corresponding package fragment root.
	 * </p>
	 * <p>
	 * Note that there is no need to supply a pattern to exclude ".class" files
	 * because a source entry filters these out automatically.
	 * </p>
	 * <p>
	 * The pattern mechanism is similar to Ant's. Each pattern is represented as
	 * a relative path. The path segments can be regular file or folder names or
	 * simple patterns involving standard wildcard characters.
	 * </p>
	 * <p>
	 * '*' matches 0 or more characters within a segment. So <code>*.java</code>
	 * matches <code>.java</code>, <code>a.java</code> and
	 * <code>Foo.java</code>, but not <code>Foo.properties</code> (does not
	 * end with <code>.java</code>).
	 * </p>
	 * <p>
	 * '?' matches 1 character within a segment. So <code>?.java</code>
	 * matches <code>a.java</code>, <code>A.java</code>, but not
	 * <code>.java</code> or <code>xyz.java</code> (neither have just one
	 * character before <code>.java</code>).
	 * </p>
	 * <p>
	 * Combinations of *'s and ?'s are allowed.
	 * </p>
	 * <p>
	 * The special pattern '**' matches zero or more segments. A path like
	 * <code>tests/</code> that ends in a trailing separator is interpreted as
	 * <code>tests/&#42;&#42;</code>, and would match all files under the the
	 * folder named <code>tests</code>.
	 * </p>
	 * <p>
	 * Examples:
	 * <ul>
	 * <li> <code>tests/&#42;&#42;</code> (or simply <code>tests/</code>)
	 * matches all files under a root folder named <code>tests</code>. This
	 * includes <code>tests/Foo.java</code> and
	 * <code>tests/com/example/Foo.java</code>, but not
	 * <code>com/example/tests/Foo.java</code> (not under a root folder named
	 * <code>tests</code>). </li>
	 * <li> <code>tests/&#42;</code> matches all files directly below a root
	 * folder named <code>tests</code>. This includes
	 * <code>tests/Foo.java</code> and <code>tests/FooHelp.java</code> but
	 * not <code>tests/com/example/Foo.java</code> (not directly under a
	 * folder named <code>tests</code>) or <code>com/Foo.java</code> (not
	 * under a folder named <code>tests</code>). </li>
	 * <li> <code>&#42;&#42;/tests/&#42;&#42;</code> matches all files under
	 * any folder named <code>tests</code>. This includes
	 * <code>tests/Foo.java</code>, <code>com/examples/tests/Foo.java</code>,
	 * and <code>com/examples/tests/unit/Foo.java</code>, but not
	 * <code>com/example/Foo.java</code> (not under a folder named
	 * <code>tests</code>). </li>
	 * </ul>
	 * </p>
	 * 
	 * @return the possibly empty list of resource exclusion patterns associated
	 *         with this source entry, and <code>null</code> for other kinds
	 *         of classpath entries
	 * @since 2.1
	 */
	IPath[] getExclusionPatterns();

	/**
	 * Returns the set of patterns used to explicitly define resources to be
	 * included with this source entry.
	 * <p>
	 * When no inclusion patterns are specified, the source entry includes all
	 * relevent files in the resource tree rooted at this source entry's path.
	 * Specifying one or more inclusion patterns means that only the specified
	 * portions of the resource tree are to be included. Each path specified
	 * must be a relative path, and will be interpreted relative to this source
	 * entry's path. File patterns are case-sensitive. A file matched by one or
	 * more of these patterns is included in the corresponding package fragment
	 * root unless it is excluded by one or more of this entrie's exclusion
	 * patterns. Exclusion patterns have higher precedence than inclusion
	 * patterns; in other words, exclusion patterns can remove files for the
	 * ones that are to be included, not the other way around.
	 * </p>
	 * <p>
	 * See {@link #getExclusionPatterns()} for a discussion of the syntax and
	 * semantics of path patterns. The absence of any inclusion patterns is
	 * semantically equivalent to the explicit inclusion pattern
	 * <code>&#42;&#42;</code>.
	 * </p>
	 * <p>
	 * Examples:
	 * <ul>
	 * <li> The inclusion pattern <code>src/&#42;&#42;</code> by itself
	 * includes all files under a root folder named <code>src</code>. </li>
	 * <li> The inclusion patterns <code>src/&#42;&#42;</code> and
	 * <code>tests/&#42;&#42;</code> includes all files under the root folders
	 * named <code>src</code> and <code>tests</code>. </li>
	 * <li> The inclusion pattern <code>src/&#42;&#42;</code> together with
	 * the exclusion pattern <code>src/&#42;&#42;/Foo.java</code> includes all
	 * files under a root folder named <code>src</code> except for ones named
	 * <code>Foo.java</code>. </li>
	 * </ul>
	 * </p>
	 * 
	 * @return the possibly empty list of resource inclusion patterns associated
	 *         with this source entry, and <code>null</code> for other kinds
	 *         of classpath entries
	 * @since 3.0
	 */
	IPath[] getInclusionPatterns();

	/**
	 * Returns the full path to the specific location where the builder writes
	 * <code>.class</code> files generated for this source entry (entry kind
	 * <code>CPE_SOURCE</code>).
	 * <p>
	 * Source entries can optionally be associated with a specific output
	 * location. If none is provided, the source entry will be implicitly
	 * associated with its project default output location (see
	 * <code>IJavaProject#getOutputLocation</code>).
	 * </p>
	 * <p>
	 * NOTE: A specific output location cannot coincidate with another
	 * source/library entry.
	 * </p>
	 * 
	 * @return the full path to the specific location where the builder writes
	 *         <code>.class</code> files for this source entry, or
	 *         <code>null</code> if using default output folder
	 * @since 2.1
	 */
	IPath getOutputLocation();

	/**
	 * Returns the path of this classpath entry.
	 * 
	 * The meaning of the path of a classpath entry depends on its entry kind:
	 * <ul>
	 * <li>Source code in the current project (<code>CPE_SOURCE</code>) -
	 * The path associated with this entry is the absolute path to the root
	 * folder. </li>
	 * <li>A binary library in the current project (<code>CPE_LIBRARY</code>) -
	 * the path associated with this entry is the absolute path to the JAR (or
	 * root folder), and in case it refers to an external JAR, then there is no
	 * associated resource in the workbench.
	 * <li>A required project (<code>CPE_PROJECT</code>) - the path of the
	 * entry denotes the path to the corresponding project resource.</li>
	 * <li>A variable entry (<code>CPE_VARIABLE</code>) - the first segment
	 * of the path is the name of a classpath variable. If this classpath
	 * variable is bound to the path <it>P</it>, the path of the corresponding
	 * classpath entry is computed by appending to <it>P</it> the segments of
	 * the returned path without the variable.</li>
	 * <li> A container entry (<code>CPE_CONTAINER</code>) - the path of the
	 * entry is the name of the classpath container, which can be bound
	 * indirectly to a set of classpath entries after resolution. The
	 * containerPath is a formed by a first ID segment followed with extra
	 * segments that can be used as additional hints for resolving this
	 * container reference (also see <code>IClasspathContainer</code>). </li>
	 * </ul>
	 * 
	 * @return the path of this classpath entry
	 */
	IPath getPath();

	/**
	 * Returns the path to the source archive or folder associated with this
	 * classpath entry, or <code>null</code> if this classpath entry has no
	 * source attachment.
	 * <p>
	 * Only library and variable classpath entries may have source attachments.
	 * For library classpath entries, the result path (if present) locates a
	 * source archive or folder. This archive or folder can be located in a
	 * project of the workspace or outside thr workspace. For variable classpath
	 * entries, the result path (if present) has an analogous form and meaning
	 * as the variable path, namely the first segment is the name of a classpath
	 * variable.
	 * </p>
	 * 
	 * @return the path to the source archive or folder, or <code>null</code>
	 *         if none
	 */
	IPath getSourceAttachmentPath();

	/**
	 * Returns the path within the source archive or folder where package
	 * fragments are located. An empty path indicates that packages are located
	 * at the root of the source archive or folder. Returns a non-<code>null</code>
	 * value if and only if <code>getSourceAttachmentPath</code> returns a
	 * non-<code>null</code> value.
	 * 
	 * @return the path within the source archive or folder, or
	 *         <code>null</code> if not applicable
	 */
	IPath getSourceAttachmentRootPath();

	/**
	 * Returns whether this entry is exported to dependent projects. Always
	 * returns <code>false</code> for source entries (kind
	 * <code>CPE_SOURCE</code>), which cannot be exported.
	 * 
	 * @return <code>true</code> if exported, and <code>false</code>
	 *         otherwise
	 * @since 2.0
	 */
	boolean isExported();

	/**
	 * This is a helper method, which returns the resolved classpath entry
	 * denoted by an entry (if it is a variable entry). It is obtained by
	 * resolving the variable reference in the first segment. Returns <node>null</code>
	 * if unable to resolve using the following algorithm:
	 * <ul>
	 * <li> if variable segment cannot be resolved, returns <code>null</code></li>
	 * <li> finds a project, JAR or binary folder in the workspace at the
	 * resolved path location</li>
	 * <li> if none finds an external JAR file or folder outside the workspace
	 * at the resolved path location </li>
	 * <li> if none returns <code>null</code></li>
	 * </ul>
	 * <p>
	 * Variable source attachment is also resolved and recorded in the resulting
	 * classpath entry.
	 * <p>
	 * 
	 * @return the resolved library or project classpath entry, or <code>null</code>
	 *         if the given path could not be resolved to a classpath entry
	 *         <p>
	 *         Note that this deprecated API doesn't handle CPE_CONTAINER
	 *         entries.
	 * 
	 * @deprecated - use JavaCore.getResolvedClasspathEntry(...)
	 */
	IClasspathEntry getResolvedEntry();
}